Voltstick Question

[Hawkmoon]

Did you touch it first to get the light then leave it --- somehow the signal is locked in from you?

Does it do the same if you leave it on the cable with it unpluged (no power) then plug in so you have power and you havent touched it?

As this

 

[snowhead]

Did you touch it first to get the light then leave it --- somehow the signal is locked in from you?

When I took the photo, Yes, see below.

Does it do the same if you leave it on the cable with it unpluged (no power) then plug in so you have power and you havent touched it?

Yes, I've now tried it by placing on the cable and switching on afterwards.
It makes no difference, it still lights up.

They look for frequency within a 50 /60 hz range and with my Fluke with a voltage over 200v.

Neutral has 50 hz on it but not 200+v

You can get them for 120volt detection.

 

[Hawkmoon]

Look up capacitive coupling and how it works and you will understand how some volts sticks dont need to be held to light up as they ref' the AC waveform to that of the DC battery circuit to establish if something is live.

• 

The waveform abobe shows the voltage rise and fall this is what the pens are looking at - the traight line in the middle is 0v and a reflection of the N wire... don't confuse this with current which is reflected the same in L and N

But all the voltstick will see is an oscillating magnetic field from both live and neutral cables alternately (ac wave), how is the dc battery circuit 'common' to either of these? (if you get what I mean)

The voltstick just senses two conductors doing exactly the same thing (at different times).


Or am I just not getting this? lol

 

[Hawkmoon]

Also why was this thread moved?? I wasn't asking 'where can I buy one'!!!!

This post was about theory - posted where the 'brains' mostly hang out (DW etc)


Why move this and leave posts like:

'What screwdriver do you find best'
'Honeywell Galaxy G2'
'Megger 1730'

?????????

 

[Darkwood]

But all the voltstick will see is an oscillating magnetic field from both live and neutral cables alternately (ac wave), how is the dc battery circuit 'common' to either of these? (if you get what I mean)

The voltstick just senses two conductors doing exactly the same thing (at different times).

Or am I just not getting this? lol

These modern volt sticks don't work like the old ones sensing a magnetic field which pulls in a leaf contact they use a control circuit board to filter false signals etc they use capacitive coupling this allows it to use the voltage waveform of the Live wire to switch components in the dc circuit they are only looking for voltage level and its cyclic waveform not current flow this cyclic component of the voltage is only present in the live conductor at the voltages the pen is sensitive to.

Capacitive coupling could be done in a few ways as ive mentioned it can use the dc battery circuit or the capacitive effect of everything around the pen that is not within its voltage pick-up range.

This is slightly out of my field of knowledge but im just theorising and putting the pieces together with what i do know .... but eether-either-or the best place to put these testers is the bin!

 

[Hawkmoon]

These modern volt sticks don't work like the old ones sensing a magnetic field which pulls in a leaf contact they use a control circuit board to filter false signals etc they use capacitive coupling this allows it to use the voltage waveform of the Live wire to switch components in the dc circuit they are only looking for voltage level and its cyclic waveform not current flow this cyclic component of the voltage is only present in the live conductor at the voltages the pen is sensitive to.

Capacitive coupling could be done in a few ways as ive mentioned it can use the dc battery circuit or the capacitive effect of everything around the pen that is not within its voltage pick-up range.

This is slightly out of my field of knowledge but im just theorising and putting the pieces together with what i do know .... but eether-either-or the best place to put these testers is the bin!

Guessing you're right - just have to 'mull over it' until penny drops

 

[SPARTYKUS]

This link is interesting- What Do You Know About Capacitive Voltage Sensors? | content content from Electrical Construction & Maintenance (EC&M) Magazine

 

[Hawkmoon]

This link is interesting- What Do You Know About Capacitive Voltage Sensors? | content content from Electrical Construction & Maintenance (EC&M) Magazine

Yeah nice link - but it does imply that the voltstick (sensor) will not operate if you are not holding it...strangely that is not the case.

But it does make clearer what DW has been describing

 

[Badged01]

All so confusing! Having had a few sherberts watching a good Bath victory at the rugby, I shall read this with interest tomorow and fully digest the contents but I do like Darkwoods explanation :smiley2:

 

[jaypp]

They will, if the Neutral isn't connected at the source,, maybe a clue there.

Last week an appliance fed from double pole SFS wasn't working. Voltstick showed voltage at every point to appliance and, when on T&E from spur, indicated it on both 'edges'. Spur was faulty and was only switching on the line conductor.